HDL, LDL . . . we hear those initials so often that they may as well be monogrammed on our bathroom towels.
But cholesterol counts are just one of a zillion things our blood can tell us about our health, notes Dean Rinard, M.D., an internist for Mercy Medical Group.
“Blood tests are irreplaceable,” says Rinard. “They’re the cornerstone of most of what we do.”
Some are nondiagnostic, such as the lipid and chemistry panels that are part of a routine physical. Others are diagnostic, helping doctors to pin things down (or rule things out) when a patient complains of symptoms. And while too much testing is not a good thing—it’s expensive and often doesn’t provide useful information, experts say—there are a number of blood tests that may, in some cases, be illuminating and even lifesaving.
Here are eight:
CRP: With heart disease still the nation’s No. 1 killer, there is much ado about the C-reactive protein test, a marker for inflammation correlated with coronary artery disease. Although the test is nonspecific, measuring overall levels of inflammation in the body—people with arthritis or the flu, to name a few, will also test with higher levels of CRP—it can signal a raised risk of heart attack, giving patients a chance to make changes in their health and fitness regimens before the inevitable occurs. “Right now, there are no standards or guidelines for CRP testing because the people who do the guidelines aren’t convinced enough that people need it,” says Ron Cotterel, M.D., director of the Sutter Center for Integrative Health in Davis. But Cotterel often uses it for patients with high cholesterol, family history or other risk factors for cardiovascular disease—and a growing number of doctors are jumping on the bandwagon.
Hepatitis C: Just because you never shot drugs doesn’t mean you aren’t at risk for hepatitis C—and it’s asymptomatic 80 percent of the time. These are just two good reasons for a hep C test, says Mercy’s Rinard. “People often have the infection and don’t know it,” he says. “There are treatments that can help, so detection is important.” The Centers for Disease Control and Prevention recommends the test only for certain high- and intermediate-risk groups, including injecting drug users and hemodialysis patients. But anyone who thinks he or she may have been exposed should be tested, says Rinard, who also runs the test (along with hep A and B) at the slightest sign of an abnormal liver reading during routine blood screening.
Hemoglobin A1C: Typically used to monitor progress in diabetes patients, the A1C test—which averages blood glucose levels over a three-month period—also may serve as a red flag for those who are tiptoeing toward diabetes. “If you test on the higher level of blood sugar levels over the three-month period, it can be a warning sign [of diabetes],” says Cheree Dunbar, M.D., a preventive medicine specialist who practices “age management medicine” in Folsom. While most doctors wouldn’t use it as first-line screening, Dunbar believes the A1C has a valuable place in preventive medicine—and it’s included in the extensive blood panel she runs on every new patient.
Homocysteine: Pop B vitamins, reduce homocysteine, reduce risk of heart attack and stroke? Whoa, not so fast: The jury’s still out on that one, according to the American Heart Association. But it’s a theory that seems to make sense, since high levels of the amino acid are linked with increased risk of coronary heart disease, and since folic acid and other B vitamins help to break down homocysteine in the body. “If you supplement with B vitamins, it may help to reduce homocysteine levels,” suggests Cotterel. He lumps the homocysteine test in the same camp as CRP because it targets the same group: those at high risk for cardiovascular disease.
Hormone panel: “People feel better and perform better when their hormone levels are at the upper end of the normal range,” says Dunbar, who runs a complete hormone panel on all her patients. Although it’s normal for hormone levels to drop with age, sometimes they decrease “more than they should,” she says—and that’s when she’ll suggest hormone therapy. “We’re not trying to ramp it up like athletes, but just keep it in the normal range for someone’s age.” Among her hormonal hit list: free testosterone, DHT (dihydrotestosterone), DHEA, estradiol, progesterone, insulin. A complete thyroid panel is especially important, she says—one that includes not just TSH but free T3 and T4, which provides a more complete picture.
Iron: Sure, we all get our iron tested when we’re having a routine checkup. But it’s not all about anemia. On the flip side is iron overload, or hemochromatosis, one of the most common genetic diseases in the United States, according to the National Heart, Lung, and Blood Institute. But it’s not always hereditary, notes Rinard: It can also be the result of too many blood transfusions, or from taking too much iron. “It’s something to watch for in hemophiliacs who frequently have transfusions, or in people with a family history of the disease,” he says. The cure? Therapeutic phlebotomy—better known as bloodletting.
PSA: When his male patients turn 50, Cotterel offers them the prostate-specific antigen test—and most opt to take it, he says. Although there is a high false-positive rate with this screening test for prostate cancer, Cotterel is a big advocate because he’s seen it save lives. Also pro-PSA is Mercy’s Rinard. “Different authorities have given different recommendations, but every man should have it after age 50, and even sooner if you have a strong family history of prostate cancer, or if you’re African-American,” says Rinard. “I firmly believe in it.”
Vitamin D: Vitamin D testing is coming into vogue, and not just because a lack of the “sunshine” vitamin can lead to weak bones: It also significantly raises the risk of heart attack, heart failure or stroke. According to a Framingham Heart Study published earlier this year, risk factors are doubled for those with blood levels of vitamin D below 15 nanograms per millilter. “The thinking on vitamin D is changing,” according to Cotterel, who says it came into disfavor in the 1940s and ’50s, when many children developed hypercalcemia (elevated calcium in the blood) by overdosing on milk. But the pendulum is swinging. “I use the test not just because of cardiovascular risk, but also if there are immune problems, which are also correlated with low vitamin D levels,” says Cotterel. It’s also a smart test for menopausal women, who have more than hot flashes to worry about: Women with low estrogen are vulnerable to bone mineral loss and, potentially, osteoporosis.
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